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| [[Image:1v83.gif|left|200px]] | | {{Seed}} |
| | [[Image:1v83.png|left|200px]] |
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| {{STRUCTURE_1v83| PDB=1v83 | SCENE= }} | | {{STRUCTURE_1v83| PDB=1v83 | SCENE= }} |
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| '''Crystal structure of human GlcAT-P in complex with Udp and Mn2+'''
| | ===Crystal structure of human GlcAT-P in complex with Udp and Mn2+=== |
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| ==Overview==
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| The HNK-1 carbohydrate epitope is found on many neural cell adhesion molecules. Its structure is characterized by a terminal sulfated glucuronyl acid. The glucuronyltransferases, GlcAT-P and GlcAT-S, are involved in the biosynthesis of the HNK-1 epitope, GlcAT-P as the major enzyme. We overexpressed and purified the recombinant human GlcAT-P from Escherichia coli. Analysis of its enzymatic activity showed that it catalyzed the transfer reaction for N-acetyllactosamine (Galbeta1-4GlcNAc) but not lacto-N-biose (Galbeta1-3GlcNAc) as an acceptor substrate. Subsequently, we determined the first x-ray crystal structures of human GlcAT-P, in the absence and presence of a donor substrate product UDP, catalytic Mn(2+), and an acceptor substrate analogue N-acetyllactosamine (Galbeta1-4GlcNAc) or an asparagine-linked biantennary nonasaccharide. The asymmetric unit contains two independent molecules. Each molecule is an alpha/beta protein with two regions that constitute the donor and acceptor substrate binding sites. The UDP moiety of donor nucleotide sugar is recognized by conserved amino acid residues including a DXD motif (Asp(195)-Asp(196)-Asp(197)). Other conserved amino acid residues interact with the terminal galactose moiety of the acceptor substrate. In addition, Val(320) and Asn(321), which are located on the C-terminal long loop from a neighboring molecule, and Phe(245) contribute to the interaction with GlcNAc moiety. These three residues play a key role in establishing the acceptor substrate specificity. | | The line below this paragraph, {{ABSTRACT_PUBMED_14993226}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 14993226 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_14993226}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Hnk-1 epitope]] | | [[Category: Hnk-1 epitope]] |
| [[Category: Transferase]] | | [[Category: Transferase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 12:12:02 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 17:01:27 2008'' |
